1. Field of the Invention
The invention relates to a method for fabricating semiconductor device, and more particularly, to a method of utilizing sidewall image transfer (SIT) process for fabricating gate structures.
2. Description of the Prior Art
Integrated circuit (IC) technologies are constantly being improved. Such improvements frequently involve scaling down device geometries to achieve lower fabrication costs, higher device integration density, higher speeds, and better performance. Lithography is frequently used for forming components of an integrated circuit device, where generally, an exposure tool passes light through a mask or reticle and focuses the light onto a resist layer of a wafer, resulting in the resist layer having an image of integrated circuit components therein. Forming device patterns with smaller dimensions is limited by a resolution of the exposure tool. For example, forming fin-like field effect (FinFET) devices with less than two fins is limited by current lithography resolution limits. Accordingly, although existing lithography techniques have been generally adequate for their intended purposes, as device scaling down continues, they have not been entirely satisfactory in all respects.